From 9/11 to the Paris attacks, from Ebola to Isis, every major global event attracts a corresponding counter-narrative from the ‘truthers’, some so all-encompassing that they take over people’s lives. Are our brains wired to believe, as a new book argues? And could such thinking actually be beneficial?

“I remember reading about Final Fantasy VII, a movie I was really looking forward to. My initial reaction was disappointment that it was two years away – because by then we’d be under military control.” It was 2004, and Matthew Elliott was in deep. Elliott, from San Antonio, Texas, had first been drawn to conspiracy theories when he was 19, in the aftermath of 9/11. “It seemed unfathomable that we could be attacked,” he says today. In his quest to make sense of what had happened he came across the notorious “truther” movement , a current of opinion that lays blame for the atrocities at the door of the US government.

“The way most conspiracy theories are laid out, one thing always leads to another, so from there I became convinced that a ruling group called the New World Order orchestrated everything. This would all lead to martial law and a complete removal of our freedoms,” he says. A decade later, Elliott, now 34, is a “recovering” conspiracy theorist, having turned his back on a worldview that always posits some covert, powerful force acting against the interests of ordinary people. The change came gradually, but he thinks very differently now. “You can’t even get many of the 50 states to agree on things. Good luck convincing Europeans and Asians to get on board.”

Elliott’s reaction to the trauma of 9/11 was far from unusual. The attacks were so unprecedented, so devastating, that many of us struggled to make sense of them. Early reports were confused or contradictory: as a result some treated the official version of events with scepticism. A proportion of those in turn plumped for an explanation that would require fakery and coordination on a massive scale.

This shouldn’t surprise us: it’s a pattern that is repeated after every global shock, and in the aftermath of the Paris attacks, it has reared its head again. Within a day of the terrorist attacks on the French capital, blogs had been published arguing that they were the work of the government – a so-called “false flag” operation. The claims rest on the idea that Isis is the deliberate creation of western governments. More recently, the lawyer for the family of Syed Farook, one of the San Bernardino shooters, fuelled conspiratorial speculation when he said: “There’s a lot of motivation at this time to emphasise or create incidents that will cause gun control or prejudice or hatred towards the Muslim community.”

Round-the-clock coverage of global events means there is a constant supply of crisis and chaos for us to interpret. Stories of strings being pulled by hidden hands are a staple of our entertainment, from Spectre’s Blofeld to the baroque conspiracy of London Spy , one of the most acclaimed British dramas of the year, which unravelled in a spectacular example of the paranoid style. It’s not that belief in conspiracy theories is becoming more widespread, says Viren Swami , professor of social psychology at Anglia Ruskin university: while the research hasn’t been done yet, he tells me, there’s lots of anecdotal evidence to suggest that belief in conspiracies has remained fairly stable for the last half-century or so. What has changed, however, is the speed with which new theories are formed. “It’s a symptom of a much more integrated world,” he says. The internet speeds everything up, allowing conspiracy-minded individuals to connect and formulate their ideas. In contrast, it took months for theories about Pearl Harbor to develop.

Karen Douglas, another social psychologist, echoes this point. “People’s communication patterns have changed quite a lot over the last few years. It’s just so much easier for people to get access to conspiracy information even if they have a little seed of doubt about an official story. It’s very easy to go online and find other people who feel the same way as you.”

Is everyone prone to this kind of thinking, or is it the preserve of an extreme fringe? Douglas reckons it’s more common than most of us realise. “ Recent research has shown that about half of Americans believe at least one conspiracy theory,” she says. “You’re looking at average people; people you might come across on the street.”

That’s also the view of Rob Brotherton , whose new book, Suspicious Minds, explores the traits that predispose us to belief in conspiracies. He cautions against sitting in judgment, since all of us have suspicious minds – and for good reason. Identifying patterns and being sensitive to possible threats is what has helped us survive in a world where nature often is out to get you. “Conspiracy theory books tend to come at it from the point of view of debunking them. I wanted to take a different approach, to sidestep the whole issue of whether the theories are true or false and come at it from the perspective of psychology,” he says. “The intentionality bias, the proportionality bias, confirmation bias. We have these quirks built into our minds that can lead us to believe weird things without realising that’s why we believe them.”

“Whenever anything ambiguous happens, we have this bias towards assuming that it was intended – that somebody planned it, that there was some kind of purpose or agency behind it, rather than thinking it was just an accident, or chaos, or an unintended consequence of something.” This intentionality bias, Brotherton says, can be detected from early childhood. “If you ask a young kid why somebody sneezed, the kid thinks that they did it on purpose, that the person must really enjoy sneezing. It’s only after about the age of four or five that we begin to learn that not everything that everybody does is intended. We’re able to override that automatic judgment. But research shows that it still stays with us even into adulthood.”

For example, studies have shown that when people drink alcohol , they are more likely to interpret ambiguous actions as having been deliberate. “So if you’re at the pub and somebody jostles you and spills your drink, if it’s your first drink, you might write it off as an innocent mistake. But if you’re a few drinks in, then you’re more likely to think they did it on purpose, that it was an aggressive act.”

Like most personality traits, proneness to intentionality bias varies across the population. “Some people are more susceptible to it than others.” And, Brotherton explains, there is a small but reliable correlation between that susceptibility and belief in conspiracy theories.

External factors also play a part, of course. For Ryan, who asked that I omit his last name, the influence of a single charismatic individual was crucial. It was Johnny, a friend and bandmate, who showed him books and CDs about world government and “served as a guru of sorts”. At the same time as inducting him into the truther movement, “he was introducing me to music I’d never heard and really loved”. At the height of his involvement, Ryan says he believed a broad range of conspiracy theories, including “ chemtrails ” – the idea that the trails left by planes contain noxious chemicals intended to subdue or poison people; that Aids and Ebola were introduced by governments to control population; that the moon landings were faked ; that a substance extracted from apricots called laetrile was an effective cure for cancer, but had been banned by the FDA and dismissed as quackery to protect the interests of Big Pharma. “I strained my relationships with my family badly. It’s always the ones you love the most that you want to ‘wake up’. I ended up in hugely embarrassing debates and arguments,” he says.

But beyond the anguish it caused for those close to him, were Ryan’s unorthodox beliefs harmful? Karen Douglas is wary of rubbishing all conspiracy theorising as dangerous. “Thinking in that way, it must have some positive consequences. If everybody went around just accepting what they were told by governments, officials, pharmaceutical companies, whoever, then we would be a bunch of sheep, really”. On the other hand, the effects of certain theories on behaviour can be damaging. Douglas’s own research [ pdf download ] has shown that exposure to the idea that the British government was involved in the death of Princess Diana reduced people’s intention to engage in politics. Similarly, subjects who read a text stating that climate change was a hoax by scientists seeking funding were less likely to want to take action to reduce their carbon footprint. And anti-vaccine conspiracy narratives make people less likely to vaccinate their children, a clear public health risk.

If everybody just accepted what they were told by governments and pharmaceutical companies, we would be a bunch of sheep

Karen Douglas

Should we try to stamp conspiracy theories out, then? Part of Brotherton’s argument is that they’re a natural consequence of the way our brains have evolved. Not only that, but trying to disprove them can backfire. “Any time you start trying to debunk conspiracy theories, for the people who really believe, that’s exactly what they would expect if the conspiracy were real,” he says.

Swami sees things differently. “Experimental work that we’ve done shows that it’s possible to reduce conspiracist ideation.” How? Swami found that people who had been encouraged to think analytically during a verbal task were less likely to accept conspiracy theories afterwards. For him, this hints at an important potential role for education. “The best way is, at a societal level, to promote analytical thinking, to teach critical thinking skills.” But that’s not all. When people have faith in their representatives, understand what they are doing and trust that they are not corrupt, they are less likely to believe in coverups. That’s why political transparency ought to be bolstered wherever possible – and corporate transparency, too. “A lot of people have trouble accepting a big organisation’s or government’s narratives of an event, because they’re seen as untrustworthy, they’re seen as liars,” argues Swami.

Improved teaching and changes in political and business culture would undoubtedly help. But conspiracy theories can be rejected for personal reasons, too. Ryan’s view changed with loss of his “guru”.

“I kinda dropped out of contact with Johnny after he got married and had a baby,” he says. “He was getting further and further into it, and I just couldn’t keep up with the mental gymnastics involved.” He started to look for alternative explanations – less exciting, but more plausible ones. “I looked at the people debating on the national level, for the presidency and such. No way these guys speaking in platitudes and generalisations could really be behind a global conspiracy to enslave or kill me. They weren’t doing a particularly good job of it either, considering how happy I was living my life.

“That was the epiphany, really. I was free. I was happy. None of the doom and gloom predicted and promised ever came.” For Ryan, by then 27, the bizarre ride was over. A world that pitted him against the forces of evil had all the appeal of a spy drama. But real life was less like a story – and in some ways more depressing. What does he think are the forces that really shape things? “Most of what is wrong in the world nowadays – well, I would put it down to incompetence and greed. A lack of compassion.”